Sequential Monte Carlo localization in topometric appearance maps.

Representing the scene appearance by a global image descriptor (BoW, NetVLAD, etc.) is a widely adopted choice to address Visual Place Recognition (VPR). The main reasons are that appearance descriptors can be effectively provided with radiometric and perspective invariances as well as they can deal with large environments because of their compactness. However, addressing metric localization with such descriptors (a problem called Appearance-based Localization or AbL) achieves much poorer accuracy than those techniques exploiting the observation of 3D landmarks, which represent the standard for visual localization. In this paper, we propose ALLOM (Appearance-based Localization with Local Observation Models) which addresses AbL by leveraging the topological location of a robot within a map to achieve accurate metric estimations. This topology-assisted metric localization is implemented with a sequential Monte Carlo Bayesian filter that applies a specific observation model for each different place of the environment, thus taking advantage of the local correlation between the pose and the appearance descriptor within each region. ALLOM also benefits from the topological structure of the map to detect eventual robot loss-of-tracking and to effectively cope with its relocalization by applying VPR. Our proposal demonstrates superior metric localization capability compared to different state-of-the-art AbL methods under a wide range of situations.This work was supported by the Government of Spain in part under grant FPU17/04512, in part under the ARPEGGIO (PID2020-117057GB-I00) research project, and also by the Andalucian Regional Government under the Houndbot (PY20 01302) research project

Indoor Positioning and Navigation

In recent years, rapid development in robotics, mobile, and communication technologies has encouraged many studies in the field of localization and navigation in indoor environments. An accurate localization system that can operate in an indoor environment has considerable practical value, because it can be built into autonomous mobile systems or a personal navigation system on a smartphone for guiding people through airports, shopping malls, museums and other public institutions, etc. Such a system would be particularly useful for blind people. Modern smartphones are equipped with numerous sensors (such as inertial sensors, cameras, and barometers) and communication modules (such as WiFi, Bluetooth, NFC, LTE/5G, and UWB capabilities), which enable the implementation of various localization algorithms, namely, visual localization, inertial navigation system, and radio localization. For the mapping of indoor environments and localization of autonomous mobile sysems, LIDAR sensors are also frequently used in addition to smartphone sensors. Visual localization and inertial navigation systems are sensitive to external disturbances; therefore, sensor fusion approaches can be used for the implementation of robust localization algorithms. These have to be optimized in order to be computationally efficient, which is essential for real-time processing and low energy consumption on a smartphone or robot

City-scale continuous visual localization

Visual or image-based self-localization refers to the recovery of a camera's position and orientation in the world based on the images it records. In this paper, we deal with the problem of self-localization using a sequence of images. This application is of interest in settings where GPS-based systems are unavailable or imprecise, such as indoors or in dense cities. Unlike typical approaches, we do not restrict the problem to that of sequence-to-sequence or sequence-to-graph localization. Instead, the image sequences are localized in an image database consisting on images taken at known locations, but with no explicit ordering. We build upon the Gaussian Process Particle Filter framework, proposing two improvements that enable localization when using databases covering large areas: 1) an approximation to Gaussian Process regression is applied, allowing execution on large databases. 2) we introduce appearance-based particle sampling as a way to combat particle deprivation and bad initialization of the particle filter. Extensive experimental validation is performed using two new datasets which are made available as part of this publication